Deformation behavior of Zr 55.9Cu 18.6Ta 8Al 7.5Ni 10 bulk metallic glass matrix composite in the supercooled liquid region

Abstract

A Zr 55.9Cu 18.6Ta 8Al 7.5Ni 10 bulk metallic glass (BMG) composite with an amorphous matrix reinforced by micro-scale particles of Ta-rich solid solution was prepared by copper-mold casting. Isothermal compression tests of the BMG composite were carried out in the range from glass transition temperature (∼673 K) to onset crystallization temperature (∼769 K) determined by differential scanning calorimetry (DSC). The compressive deformation behavior of the BMG composite in the supercooled region was investigated at strain rates ranging from 1 × 10 −3 s −1 to 8 × 10 −2 s −1. It was found that both the strain rate and test temperature significantly affect the stress–strain behavior of the BMG composite in the supercooled liquid region. The alloy exhibited Newtonian behavior at low strain rates but became non-Newtonian at high strain rates. The largest compressive strain of 0.8 was achieved at a strain rate of 1 × 10 −3 s −1 at 713 K. The strain rate change method was employed to obtain the strain rate sensitivity ( m). The deformation mechanism was discussed in terms of the transition state theory based on the free volume.